Compressed gas is transported and used in elongated cylinders which are sufficiently large to meet the needs of an operating facility. For operations where large volumes of compressed gas or a continuous supply are required, cylinders which measure about 20-40 feet in length and about 1-2 feet in diameter are used. These cylinders must be capable of retaining the high pressure of the gas and of meeting regulatory requirements for safety during storage, transport and use. Among these requirements are that the cylinders be able to withstand induced loads or stresses such as those which arise during their assembly and transport as well as those resulting from exposure to extreme environmental conditions. Dangers associated with these stresses include the risk of placing undue stresses on tube connections, valves and safety devices mounted to the cylinder ends, as well as the risk of damage to the cylinders themselves. The causes of these induced loads, particularly in modules or tube traliers containing several cylinders, include:
(1) Misalignment of the cylinders during assembly of the module, the misalignment having been caused by tolerances and other irregularities introduced during manufacture of the module. PA1 (2) Tolerances in the manufacture of the cylinders themselves. PA1 (3) Expansion and contraction of cylinders due to temperature and pressure change, including variations among individual cylinders. PA1 (4) Flexure of the module frame and racking of the frame, i.e., twisting of one end relative to the other, during handling and transportation.
To withstand such stresses in cylinders of this size, a particularly strong construction is needed, and for this reason, high-strength steel is commonly used. Since the steel itself withstands the stress, the methods by which the cylinders are mounted to the module or truck bed are simple.
According to one of these methods, the cylinder neck is captured in a bulkhead by opposing jam nuts threaded onto the external surface of the neck. While this places the stress on the cylinder neck, the heavy steel construction of the neck accommodates the stress. This is acceptable for heavy steel cylinders, but not for cylinders of lower strength or fatigue resistance.
Another method involves the use of saddles to support the cylinders at intermediate locations along the lengths of the cylinders, with restraining straps to secure the cylinders to the saddles. A disadvantage of this method is that it places limits on how compact the packaging arrangement can be. Again, for steel cylinders, this is not a serious consideration, since the weight of these cylinders already limits the number of cylinders which can be combined in a single module. For cylinders of lighter material, however, compact packing is more important.
A mounting system which itself reduces the stresses of induced loads would be one which permits articulation of the cylinder relative to the bulkhead while maintaining a secure mounting connection. The system should accommodate small deviations of the cylinder axis from perpendicularity relative to the bulkhead, as well as movement in both horizontal and vertical directions. Rotation around the axis must be avoided, however, to preserve the seals on the tubing connections, and a secure mounting must be maintained. These and other problems and needs of the of cylinder mounting systems, particularly as applied to cylinders of a lighter weight than steel, are addressed by the present invention.